Development Of Blood Pressure Detection System Based On Volume Pulse Wave Gradient Method

According to Chinese cardiovascular disease reports, the number of China's annual deaths caused by cardiovascular disease continues to increase, furthermore cardiovascular disease is still the first cause of death in our population. At present,there are about 290 million people suffering from cardiovascular disease in China, of which more than 90% are hypertensive patients. Therefore, in our daily life,concerning about the change of blood pressure is important for the prevention of cardiovascular diseases. At present, Korotkoff sound method is "gold standard" in noninvasive detection of blood pressure, but it requires professionals to operate.Therefore, it is hard to be popularized in the daily life. In recent years, the electronic sphygmomanometer on the market have adopted the detection principle of oscillometric method, and its algorithm is deduced by manufacturers on the basis of a large number of experiments and has no uniform standard, so there are some errors. Volume-vibration method can detect accurately, but cannot directly measure diastolic blood pressure which is determined by the similarity between pressure wave and pulse waveform. Based on the current situation of the intermittent blood pressure measurement, this study explores a new method to detect blood pressure "volume pulse wave gradient method".The detection principle of volume pulse wave gradient method is according to nonlinear mechanical properties of the vessel wall to carry out non-invasive pressure measurement, if the pressure inside and outside the walls of blood vessels is smaller, it is more easily deformed; on the contrary, the pressure inside and outside the walls of blood vessels is larger, it is more difficultly deformed. Based on this principle of the detection of blood pressure, this study developed a blood pressure monitoring system,which is used to detect the blood pressure at the radial artery of the human body.Firstly, this study analyzes the feasibility of the "volume pulse wave gradient" method through preliminary experiment, the two detection results are compared taking the Riva-Rocci sphygmomanometer testing results as the standard. The experimental results show that this detecting principle is feasible.Secondly, this paper describes in detail the design of the module of power supply,the module of the detection of pulse wave and pressure, the driven module of pump and valve. In this system, PIC microcontroller applied the result of PID control algorithm to control pump and valve to realize increasing pressure at a consistent speed, at the same time, processing the data and finishing the detection of blood pressure.Finally, I carry out a certain amount of experimentation using this detection system and the mercury sphygmomanometer, the results are analyzed using the Bland-Altman diagram, which shows that the consistency of two detection methods is better; And then,the same experimenter carries out multiple repetitive experiments, the experiment result shows that the system has good stability.